This invention relates to a machine parts protecting system for protecting those parts of a machine that may be in close proximity to high temperature flames and, in particular, to a machine for processing workpieces which carries the workpiece from operating station to operating station in a stop-and-go fashion.
A number of machine parts protecting systems are known in the art. One such system is disclosed in U.S. Pat. No. 3,580,553, dated May 25, 1971, issued to Daniel M. Urich. This patent discloses an improved pellet hardening machine including a preheating section where pellets of iron ore are preheated and an indurating section where the preheated pellets are heated to a desired hardness. A stripper assembly is provided for removing pellets from a conveyor on which they are transported. Replacement of the stripper assembly necessitates shutting down the operation of the pellet hardening machine or assembly with a resultant decrease in plant productive time and an increase in pelletizing costs. To increase the life of the stripper assembly it is cooled by a flow of air from a pump or other source of air under pressure, thereby increasing the life of the stripper assembly.
In U.S. Pat. No. 3,480,264, dated Nov. 25, 1969, issued to Wilhelm Krause, is disclosed a metallurgical furnace wherein workpieces are transported intermittently through a heating chamber and rest on stationary holders during intervals between step-wise advances. The holders are protected by heat-insulating material and are separated from each other by narrow vertical gaps through which scale and like solids can descend but which admit little heat to the respective holders. The holders are internally cooled by a circulating fluid and have rows of plate-like work-engaging portions which extend upwardly and consist of highly heat-resistant metallic material.
In U.S. Pat. No. 3,451,661, dated June 24, 1969, issued to John S. Barker, is disclosed an arrangement for protecting and insulating water-cooled tubular support members in a furnace of the type used for heating steel ingots after the ingots have been formed into suitable shapes. An inner layer of resiliently deformed insulating material covers the support member. An outer layer of interlocking refractory elements covers the inner layer and holds it in radial compression while the inner layer in turn holds the outer layer in a state of circumferential stress. The refractory elements are designed to permit limited freedom of movement therebetween to accommodate the effects of thermal stresses and vibrational shocks.
In U.S. Pat. No. 3,687,433, dated Aug. 29, 1972, issued to Charles H. Bode, Jr., is disclosed a device for protecting a conveyor which carries metal workpieces as they undergo a flame cutting operation. The device is intended particularly for conveyors which carry continuously cast products as segments are cut therefrom. The conveyor includes endless chains and slats extending from between chains. A flame-cutting apparatus travels in synchronism with the workpiece as it cuts and sometimes lies directly over a slat. A protective device overlies such slat and the workpiece rests thereon. Damage is confined to the protective device if the flame-cutting apparatus lies directly thereover.
It is apparent from the foregoing art that the protective devices used are in continual operation during the operation of the machine. In many instances though a protective device may only be required occasionally when, for example, a workpiece is not being held by a workpiece holder. Then, instead of the workpiece being heated by high temperature flames, certain parts of the workpiece holder will be exposed to the flames with a resultant shortening in life of those parts.